Hyung-Woo Lee, "전속도 영역에서 동작하는 매입형 영구자석 동기전동기의 회전자 위치 추정 기법," 아주대학교 공학석사 학위 논문, 2022. > Paper

This thesis presents a transition method between rotor position and speed estimation methods without sensors for an interior permanent magnet 

synchronous motor (IPMSM). Through the proposed method, it is possible to estimate the rotor position for the whole speed region of the IPMSM. 

Considering that each sensorless scheme has a different operation region according to rotor speed for high estimation accuracy, a transition method 

between the two sensorless scheme is essential. In this study, a sensorless method based on extended back electromotive force (EEMF) is 

employed for high-speed operation. In addition, the rotor position during low-speed operation is estimated applying the slope of the current measured through the application time of the zero-voltage vector. The weight function is used to the position and speed information estimated by the two 

sensorless schemes. The combined information is applied throughout the whole speed region of the IPMSM. For smooth transition between the two 

sensorless methods, the weight function changes according to the rotor speed of the transition range. The effectiveness of the proposed transition 

method has been demonstrated through simulation and experiment.